定语从句as 和which 的区别讲义
which与as引导非限制性定语从句的异同
which与as引导非限制性定语从句的异同which与as一样,都可以引导非限制性定语从句,它们既有相同之处,也有差别。
因此在实际运用中容易混淆。
它们的某些用法在高考中也会考查。
一.相同点。
两者引导非限制性定语从句时,可指代主句中的部分或整个句子的内容,在从句中做主语,宾语或表语,位于主句之后有时可互换。
The meeting was put off, as /which was exactly what we wanted.He was a doctor, as/which I knew from his manner.二.不同点1. as可指其前后主句提到的事实或情况,因此引导的非限制性从句位置比较灵活,which可以放在主句前后,也可插入主句之中;而which 引导的非限制性从句只能位于主句之后。
As is known to all, fish can’t live without water.Air, as we know, is gas.2.在非限制性从句中,which后的be动词不可省;as而后的be动词可以省略。
She told me she won the match , which was a lie.The material is elastic, as (was) shown in the figure.3. which在非限制性定语从句做主语时可用各类动词做谓语;而在非限制性定语从句做主语时,谓语常用连系动词,如be, seem, become 等,一般不用其他行为动词。
He saw the girl, which delighted him.He didn’t say anything at the m eeting , as/which seemed very strange. 4. 如果主句中叙述的事情与从句所涉及的意向一致,多用as,用以对主句的意义进行补充;如果不一致,就用whichShe has married again, as was expected.He broke the rules again, which was unexpected.5.如表示“如同。
非限制性定语从句which和as的用法汇总一篇
非限制性定语从句which和as的用法汇总一篇非限制性定语从句which和as的用法 1非限制性定语从句which和as的用法一、相同之处当从句位于主句之后，引导词指代整个主句所表达的全部意义时，as 和which可以互换。
如：The elephant is like a snake,as/which everybody can see.大家都看得出，这头大象像条蛇。
A big earthquake occurred there last night,as/which was reported on TV.据电视报道，昨夜那里发生了大地震。
She is from Shanghai,as/which I know from her accent.她来自上海，那是我从她的口音知道的。
二、不同之处1、as引导非限制性定语从句时，位置比较灵活，可位于主句之前，也可位于主句之中或之后;而which引导非限制定语从句只能位于主句之后，不能位于主句之前。
如：_______ is known to everybody,the moon travels round the earth.A.ItB.AsC.ThatD.Which答案：B_______ is mentioned above,the number of the students in senior highschools is increasing.A.WhichB.AsC.ThatD.It答案：BAir,as we know,is a gas.众所周知，空气是一种气体。
He is very careful,as his work shows.他的工作表现表明他非常谨慎。
as引导非限制性定语从句常有“如同.那样”的含义，因此在一些固定结构中，如：as we know;as is known to all(众所周知)as we all can see(正如我们大家都能看到的那样)as has been said before/above(正如前面所述)as might be imagined(可以想象得到)as might be expected(正如所预料的那样)as is often the case(情况通常是这样)以上种种固定搭配，一般不能用which代替as。
高一英语as与which引导的定语从句区别课件(共15张PPT)-经典通用课件资料
4、缩放时，按Shift键及鼠标点图片选框的角部，避免变形 5、胶片尽量使用此图库，使公司资料风格统一
常用字列表 Thanks
作图元素
小区、业务平台等的表示图标，上面放终端或产品示意图
生词…短语…句型
Unit 1
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图库用法指导
1、此图标库在色彩方面大致分为鲜亮色(符号及元素)和沉稳色(各终端及实物场景)，使 用时，注意鲜亮色和沉稳色要平衡，画面不要全是鲜亮色或者全是沉稳色。
2、由于各终端及实物场景的颜色是沉稳色，所以连接它们的组网线要粗一些、颜色可 以鲜一些，以产生对比，求得视觉平衡。
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(5) 当非限制性定语从句的引导词前面有介词时，只能用which, 而不可用 as。如： He has a new computer, for which he paid nearly ten thousand yuan. 他有一台新电脑，这台电脑花了
他将近一万元。
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(6) 当关系代词代替主句中的宾语从句或复合结构(如：宾+补；不定式短语；动词-ing形式短语等) 时，一般只能用 which, 而不用 as。如：
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(9) 当关系代词仅代表主句中单个的名词时，一般只用which, 而不用as。如： He sent me a beautiful present, which I valued very much. 他给寄来了一件精美的礼物，我对它非常珍视。
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(10) as 在非限制性定语从句中，还常跟such连用。如： There was a look of love in the teacher’s eyes, such as mothers have for their children. 老师眼里
定语从句中关系代词as与which的用法
学法新探关系代词as与which在定语从句中有时可以相互替换，但又有不同之处，稍不留心，极易使用不当，出现差错。
对此，笔者剖析了关系代词as与which在定语从句中的用法，以期能够帮助同学们准确把握和运用。
一、关系代词as与which在限制性定语从句中的用法关系代词as、which均可以用于限制性定语从句中，有时可以相互替换，但两者仍有着一定的差异，具体体现在：（1）当定语从句中的先行词为某物，且先行词前面有so,such,the same，as many/much等修饰语时，则只能用as引导限制性定语从句，不能用which引导。
比如：①It’s the same book as I bought yesterday.这本书和我昨天买的一样。
（不能用which代替as）②HongKong is so prosperous a city as is referred to as a shop-ping paradise.香港是一个繁荣的城市，被称为购物天堂。
(不能用which代替as)③These housed are sold atsuch a low price as people expected.这些房子按人们预料的那样低价出售了。
(不能用which代替as)（2）当先行词是表示某物的名词或代词时，且在从句中又做介词宾语时，则不可以用as引导限制性定语从句，只能用which引导限制性定语从句。
如：①Thisis the good car on which I spent all my money.这是我花了所有钱买的那辆好车。
（不能用as代替which）③This is the knife with which we cut the bread.这是我们切面包用的刀。
（不能用as代替which）③There is amountain of which the top is always covered with snow.有一座山顶总是覆盖着雪的山。
as和which引导定语从句的区别
as和which引导定语从句的区别as和which引导定语从句的区别导语：As 和which都可以引导非限定性定语从句，在用法上有一些区别。
欢迎阅读！1.as 和which都可以在定语从句中作主语，宾语，既可修饰一个词也可修饰前面的整个句子。
A.She accepted his proposal, as(which)was natural.她接受了她的求婚，这是自然而然的。
B.The boy is pretty handsome, as(which)we can see in our classroom.这个男孩非常的帅气，正如我们在教室看到。
2.as 在非限定性定语从句中的使用2.1 as可以放在主句之前，主句之后，也可以放在句中，可以说位置很灵活。
但是which常用在主句之后A.As we know,technology just like a engine to push the development of economics.众所周知，技术就像是引擎推动着经济的'发展。
B.The diva,as you know, is famous throughoutthe world.这个女歌剧演唱家，正如你知道的，在全世界都出名。
C.He has stood her up, which I don`t believe.他没有赴约，这事我不相信。
2.2 as与the same，such 连用时，用as。
A.This is the same phone as I have borrowed from my sister.这个手机和我向我姐姐借的一样。
B.I have never had such a chance to make a speech as I always imagined.我从没有这样一个机会去演讲，正如我一直想象的那样。
2.3在从句中谓语动词为被动语态，缺少主语时用as，不用which。
as和which引导非限制性定语从句的区别
as 和which引导非限制性定语从句的区别1，as引导的非限制性定语从句，位置灵活，可以置于主句的句首、句中或句末；先行词不可是一个词，必须是整个主句或主句的部分内容；有“正如、像”等意思，表依据、评论（、态度、看法）等；如：This elephant is like a snake，as anybody can see．像任何人都能看见那样，这头象像条蛇。
He failed in the exam, as we had expected.Tom has passed the test, as everybody knows. 正如每个人所了解的那样，汤姆通过了考试。
【比较：Bamboo is hollow，which makes it very light．竹子是空的，这就使得它很轻。
】常用以下谓语动词的主、被动语态：know, see, say, expect, imagine, hope, believe, announce, suggest, report, point out…, 例：主动（做宾）：as we all know, as you know, as everybody knows; as you see, as we can see, as we have seen, as anybody can see; as was expected; as we can imagine, as we have imagined…As we all know, the earth is round.He was a foreigner, as I know from his accent.Mike, as we expected, attended the meeting．像我们所期望的那样，迈克参加了会议。
被动（做主）：as is known to everybody, as is known to all; as has been expected; as is often the case (with …)，as has been pointed out, as is usual with, as is reported in the newspaper…He is an honest man, as is known to all.As is often the case with young people, he was overconfident.He wasn't unconscious，as could be judged from his eyes．他并未失去知觉，这从他的眼神可以判断出来。
AS和Which引导非限制性定语从句
AS和Which引导非限制性定语从句关系代词as 与which引导非限制性定语从句可以用整个主句作为其先行词，指代上面或下文所说的一件事。
但何时用as，何时用which，时常出现差错。
现就as 与which在引导这种定语从句时所出现的不同词义和句法特点进行对比、分析如下。
一、as引导的从句表示说话人对话语的看法、态度、解释或评论。
一般有以下特点：1、此时的as仍具有“正如、象、由……而知、与……一致”等某些作连词时的语义。
翻译时有时可不必译出。
如：Shakespeare is a famous writer, as we all know. 莎士比亚是著名的作家，这众人皆知。
She is very patient, as is shown in her work. 她很耐心，正如她工作中所表现出来的一样。
2、在句法上，as常用作一些实意动词(如see, know, hear, watch, remember, say, tell, show, expect, guess等)的宾语，这类动词与as几乎成了一种固定搭配。
如：Einstein, as we know(=as is well known), is a famous scientist. 众所周知，爱因斯坦是一位著名的科学家。
There was a net bar around here, as I remember. 我记得这儿附近有一家网吧。
3、当从句的谓语动词是否定形式或从句谓语动词带的是一个复合宾语结构时，一般用which而不宜用as。
如：You pretended not to know me, which I didn’t understand. 他假装不认识我，我真不明白。
He admires everyone in the class, which I find quite strange. 他羡慕班里的每个学生，我认为太奇怪了。
【初中英语】定语从句as和which的用法(1)
定语从句1.非限定性定语从句——用逗号隔开作用：提供附加而非必要的信息，只是对先行词作进一步的解释、补充或者说明。
若去掉此定语从句，整个主句的意义一样很明确，不会引起误解和歧义。
eg.Beijing，which is the capital of China,has developed into a international city.如果定语从句修饰一个专有名词，我们一般要用逗号，也就是说要用非限制性定语从句。
因为专有名词本身的含义就很完整，不需要限制，用定语从句知识对它进行补充说明。
2.As的用法（1）as在引导限定性定语从句时，只是在一些固定的结构中，即只能用在such,the same, as ,so 的后面。
eg.he is not the same as we knew.（2）as引导非限定性定语从句可位于句首，而which不能这么用。
eg.As is known, the whale is not fish but a mammal.（as指的是 the whale is not a fish but a mammal.）总所周知，鲸不是鱼类，而是哺乳类动物。
（3）as和which都可以引导非限定性定语从句，代替前面的整个句子。
eg.he married her, as/which was natural.但因为as引导的定语从句有“正好...”,“就像...”,“由...而知”的含义。
所以，当主句和从句内容上一致时，或者说从句内容是顺着主句意思说下来时，用as。
若主句和从句内容上下不一致时，或从句内容对主句的内容起反对、排斥、否定等消极作用时，多用which。
eg. She has married again, as was expected.She has married again, which was unexpected.。
which与as引导定语从句的区别 之谈
which与as引导定语从句的区别之谈常见的定语从句引导词一般为关系代词：who,whom,whose,which,that 和关系副词：when,why,where. 而作为比较另类的as用作关系代词和关系副词引导的定语从句，有时候就被大家忽略了。
众所周知，which与as都可以引导定语从句，但它们有许多用法上的区别，现就此简要分析如下：一、which与as引导非限制性定语从句的区别：1.Which只能放在主句后面，而as引导的从句位置相对较灵活，可在前，可在中，也可在后。
例如：A）As he realized, I was very useful to him.（在前）B）Air, as we know, is a gas.（在中）C）He was a foreigner, as I know from his accent.（在后）2.在which引导的定语从句中，谓语动词若是am, is, are则这些系动词不能省略；而as 后面若是这种情况，则可以省略。
例如：A）He is a teacher, as （is）clear from his manner.（is可以省略）B）He said he had never seen her before, which was not true.（was不可省略）3.当which引导的从句在意义上近乎并列关系时，可以用and this，and that代替，意思是“这件事”例如：A）He changed his mind, which（and this, and that）made me very angry.他改变了主意，这使我很生气。
B）She has married again, which（=and this, and that）was unexpected.出乎意料的是，她又结婚了。
而as主要起与上下文连接的作用，表达说话人的看法、观点，并指出主句内容的出处或根据等，例如：C）Einstein, as we know, is a famous scientist.爱因斯坦，众所周知，是位伟大的科学家。
as_which引导定语从句的区别
众所周知，which与as都可以引导定语从句，但它们有许多用法上的区别，现就此简要分析如下：一、which与as引导非限制性定语从句的区别：1．Which只能放在主句后面，而as引导的从句位置相对较灵活，可在前，可在中，也可在后。
例如：A) As he realized, I was very useful to him.(在前)B) Air, as we know, is a gas.（在中）C) He was a foreigner,as I know from his accent.(在后)2.在which引导的定语从句中，谓语动词若是am, is, are则这些系动词不能省略；而as后面若是这种情况，则可以省略。
例如：A) He is a teacher, as (is) clear from his manner.(is可以省略)B) He said he had never seen her before, which was not true.(was 不可省略)3.当which引导的从句在意义上近乎并列关系时，可以用and this，and that 代替，意思是“这件事”例如：A) He changed his mind, which(and this, and that)made me very angry.他改变了主意，这使我很生气。
B) She has married again, which(=and this, and that)was unexpected.出乎意料的是，她又结婚了。
而as主要起与上下文连接的作用，表达说话人的看法、观点，并指出主句内容的出处或根据等，例如：C）Einstein, as we know, is a famous scientist.爱因斯坦，众所周知，是位伟大的科学家。
D）As is announced in today’s newspaper, we must improve our style of work.今天的报纸上说，我们必须改进工作作风。
as与which引导非限制性定语从句的区别
、。
as与which引导非限制性定语从句的区别as 的特殊用法1、如果要说明两者有相似之处时通常用as，表达“正如（情形或事实所表示）的那样、像……的一样”的意思。
例如：She is a fine singer，as her mot her used to be．她是一个很出色的歌唱家，和她母亲当年一样。
She is the same age as you (ar e). 她和你年龄一样大。
[与same...as 连用]I hope to get such a dictionary as he is using. 我希望有一本和你正在用的一样的词典。
[与such...as连用]As water is to fish, so air is to man. 正如水对鱼一样重要，空气对于人同样重要。
She has married again，as was/ seemed natural．她又结婚了，这很自然。
2、as常与从句中的know，see，h ear，expect等动词连用，也常用于as of ten happens，as is often the case（常有的事）等句子中。
As you know, he is from Beijin g. 正如你所知道的，他来自北京。
As is known to everybody，the moon travels round the earth once every month．He was absent，as is often the ca seAs you will find out, all is now set tled. 你将会看到这样的情况，一切都已搞定了。
3、as引导的非限制性定语从句的位置比较灵活，既可位于所修饰的句子之后，也可位于句中或句首；而由which引导的非限制性定语从句一般不位于句首。
例如：As you will find out，I will neve r let you down．你将会发现，我绝不会使你失望的。
As和which引导定语从句时的用法详解
As和which引导定语从句时的用法详解一、引导限制性定语从句引导限制性定语从句时，在such, as, the same后只能用as，其他情况用 which。
如：I never heard such stories as he tells. 我从未听过他讲那样的故事。
It’s the same story as I heard yesterday. 这故事跟我昨天听到的一样。
Such wind as there was came up the fiver. 当时起的这种风沿江刮了上来。
He was in such a fury as I have never seen. 我从未见过他发这么大的火。
As many as ten people were found living in a single room. 曾发现多达十个人住在一间房里。
It is an organization which helps the elderly. 这是一个帮助老年人的机构。
He possesses qualities which ensure success at school. 他有许多品质保证他学习很成功。
二、引导非限制性定语从句1. 互换的场合引导非限制性定语从句时，有时两者可互换。
如：I live a long way from work, as [which] you know. 我住得离工作单位很远，这你是知道的。
He arrived early to dust the shop, as [which] was his custom. 他到车间很早，先掸尘土，这是他的习惯。
I had coffee after dinner, as [which] is my usual practice. 我饭后喝咖啡，这是我的习惯。
Sophia was not unconscious, as [which] could be judged from he r eyes. 索菲娅并未失去知觉，这从她的眼睛里可以看出。
as和which引导的定语从句
As与which引导的定语从句先研究下面两个例句：○1.This elephant is like a snake, as /which everybody can see.=As everybody can see, this elephant is like a snake.任何人都看得出来，这头象像条蛇。
○2.Tom didn’t pass the physics exam, which made his parents very angry.Tom物理考试不及格，这使得他父亲很生气。
这两个例句中，as和which所代表的都是整个主句所表示的内容。
但有两点不同之处：1．在形式上as引导的非限制性定语从句可位于主句的后面，也可位于主句的前面；而which引导的非限制性定语从句只能位于主句的后面，不能位于主句的前面。
2．在意义上，as引导的定语从句和主句的关系一般为一致关系，常译为“正如……”，“就像……”，而which引导的定语从句和主句的关系是因果关系，或which引导的定语从句是对主句的评论。
因此，在意思通顺的情况下，which可代替as，而as许多时候不能代替which，如句○2。
再如：1．He was late again, as / which we had expected.=As we had expected, he was late again.正如我们所料，他又迟到了。
/他又迟到了这是我们早就料到的。
2．The street hasn’t been cleared for weeks, which makes it very dirty.街道好多星期没有打扫了，因此整条街很脏。
（不用as）3．The young man cheated his friend of much money, which was disgraceful.那年轻人诈骗了他朋友许多钱财，这是不光彩的。
as与which引导非限制性定语从句的区别
as与which引导非限制性定语从句的区别作者：董军权来源：《广东教育·高中》2013年第11期在教学实践中，尤其在批改作文中笔者发现，有的学生对as与which引导非限制性定语从句的用法模棱两可，含混不清。
下面从两者的用法区别展开说明，以便正确地使用。
1. 从指代的异同来说，as指代整个句子；which指代整个句子或者主句中的某个成分。
如：She is not unconscious，as can be judged from her eyes.她并未失去知觉，这从她的眼睛里可以看出。
（as指代整个句子）Mother always asked him to study hard，which helped him a lot. 他妈妈总是让他刻苦学习，这一点对他帮助很大。
（which指代整个句子）The house， which was built fifty years ago， stood still in the earthquake. 这所建造于50多年前的房子，在地震中依然耸立着。
（which指代具体的先行词）2. 就主句与从句的位置关系来说，as引导的从句可放在主句的前面或者主句的后面；which引导的从句只能放在主句的后面。
如：As everybody knows， knowledge is power. 众所周知，知识就是力量。
Knowledge is power， as everybody knows.众所周知，知识就是力量。
Knowledge is power， which is accepted widely all over the world.知识就是力量，这一点世界公认。
3. 从意义上来说，as意为“正如，像，由……而知”； which意为“这就使得，这一点”。
如：He is a great hero， as is described in the report.正如在报道中描述的一样，他是一个伟大的英雄。
as和which引导的定语从句的区别
从山东一道高考题看as和which引导的定语从句区别as 引导的定语从句可以代替整个主句内容；which引导的定语从句可以代替整个主句，有时代替主句部分内容。
那么它们有什么区别呢？1）意义上的区别（此点是关键区别）as 往往翻译为“正如”；which往往翻译为“这一点”。
Mr. Lu committed suicide, which made the whole nation sad.He passed all the examinations, as we had expected.As 往往有一些相对固定的形式as we had expected, as we all know, as is known to us all, as is/was reported, as is often the case, as it turned out, as we can remember etc.He was late for work this morning, as is often the case.2) 位置上的区别which引导的定语从句，常常位于句末，有时位于句中，一般不能位于句首；as 引导的定语从句可以位于句首，句中，句末。
She married John, which surprised us all.Whenever I met her, _________ was fairly often, she greeted me with a sweet smile.（09山东）A. whoB. whichC. whenD. thatAs we all know, the sun rises in the east and sets in the west.The sun rises in the east and sets in the west, as we all know.The sun, as we all know, rises in the east and sets in the west.小提示：Which 引导的定语从句，位于句首的情况，本人在英美人写的文章中看到过好几次。
as_which引导定语从句的区别
众所周知，which与as都可以引导定语从句，但它们有许多用法上的区别，现就此简要分析如下：一、which与as引导非限制性定语从句的区别：1．Which只能放在主句后面，而as引导的从句位置相对较灵活，可在前，可在中，也可在后。
例如：A) As he realized, I was very useful to him.(在前)B) Air, as we know, is a gas.（在中）C) He was a foreigner,as I know from his accent.(在后)2.在which引导的定语从句中，谓语动词若是am, is, are则这些系动词不能省略；而as后面若是这种情况，则可以省略。
例如：A) He is a teacher, as (is) clear from his manner.(is可以省略)B) He said he had never seen her before, which was not true.(was 不可省略)3.当which引导的从句在意义上近乎并列关系时，可以用and this，and that 代替，意思是“这件事”例如：A) He changed his mind, which(and this, and that)made me very angry.他改变了主意，这使我很生气。
B) She has married again, which(=and this, and that)was unexpected.出乎意料的是，她又结婚了。
而as主要起与上下文连接的作用，表达说话人的看法、观点，并指出主句内容的出处或根据等，例如：C）Einstein, as we know, is a famous scientist.爱因斯坦，众所周知，是位伟大的科学家。
D）As is announced in today’s newspaper, we must improve our style of work.今天的报纸上说，我们必须改进工作作风。
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名词性从句区别名词性从句是一种具有名词功能的非独立分句，可以表示：事实和问题。
1.连接词有：that whether 和lf2.连接代词有：who whom whose which what 等3.连接副词有：when where why how 等另外whatever whoever whichever等也可以引导主语和宾语两种从句名词性从句中的“that”没有词义，也不作任何成分。
除引导宾从外，主从和表从中不省1. 主语从句：从句在句中充当主语成分1) That the earth is round is true .2) Whether he will come is doubtful .3) What he said surprised me most .4) Where he hid the money is to be found out .5) Whoever comes is welcome.6) It’s certain that he will succeed7)How we can help the twins will be discussed at the meeting.8) When they’ll start the project has not been decided yetIt 的用法：（形式主语）It’ possible/important/necessary/clear… that……很可能/重要的是…/必要的是…/很清楚…It’ said/ reported… that…据说/据报道…It’s been announced/declared that…已经通知/宣布…It seems/appears/happens.. that…显然、明显、碰巧…It’s no wonder that…并不奇怪/无疑…It’s a pity/a fact /a common knowledge (众所周知）/ a common saying….（俗话说“if” 不能引导主语从句，应有“whether”引导主语从句的“that” 一般不能省。
“what”引导主语从句时，谓语动词：1）常与其后作表语的名词一致2）根据句子的语境而定。
1.What you left are only several old books.2.What you said is of great importance.3.What he says and does doesn’t concern me.4.What he says and does don’t agree2. 宾语从句：从句在句中充当宾语成分（可以作谓语动词、介词、不定式等非谓语动词的宾语）that, whether，if （that 常可省略）连词：who, what, which, whoever, whateverwhen , where , why ,how1). Can you make sure where Alice has put the goldring.2). It all depends on whether they will support us .3). She will give whoever needs help a warmsupport.4). He made it clear to the public that he did animportant and necessary job .5).I find it necessary that we should do thehomework.3. 表语从句：从句在句中充当表语成分，一般放在连系动词之后.作用：对主语进行解释说明。
连接词：that / whether /as if /as though（if 不引导表语从句)连接代词：who / whoever / which / whatever连接副词：when / where / why / how / becausee.g.China is no longer what she used to be.That’s because we were in need of moneyat that time .He looked as if he was going to cry .Tomorrow is when it would be mostconvenient.1.在表语从句中，表“是否” 时，只能用“whether”不能用“If”。
2.一般情况下，“that”不能省。
3.It is /was because ….It is /was why….3. The reason (why…/for…)is /was that….4 The reason is because /why…4 同位语从句：从句在句中充当同位语成分，一般跟在一些抽象名词（idea ；belief ；fact ；truth ；rumour ；news 等）后面，对名词作进一步解释说明同位语从句常用that/ whether引导或连接副词when / where /why / how1)The idea that computers can recognizehuman voices surprises many people .2)Word came that Napoleon himself wascoming to inspect them .同位语从句和定语从句的区别：1. 同位语从句——that 只起连接作用，不作任何成分定语从句—— that 是关系代词，起连接作用和充当宾语和主语2.同位语从句——同位语从句和前面的名词是同位关系，对名词进行补充说明定语从句——定从和前面的名词是所属关系，对名词进行修饰，加以限定3.同位语从句——that 不能省定语从句——that 在从句中作宾语时，可以省关系代词as与which的用法区别as 和which的相同点(1)as 和which都可引导非限制性定语从句，放在主句之后；在非限制性定语从句中充当从句的主语、宾语或表语。
如：Tom has found a good job, as / which we all hope. 汤姆找到了一件好工作，这正是我们大家所希望的。
(2)as 和which都可代表整个句子的内容或主句中的某一成分。
如：His mother is ill, which makes him very sad. 他母亲病了，这件事情使他很难过。
He has made great progress, as / which makes us very happy. 他进步了，这使得我们很高兴。
以上两句中的as / which都指前面整个句子的内容。
Though he has lots of money, he still rides his old bike, which was boug ht ten years ago. 尽管他很有钱，但是他还骑着他的旧单车，这单车是十年前买的。
There you can meet many writers as you have ever read in books. 在那里，你可见到你在书中所读过的很多作家。
as与which的区别(1)当先行词前面有so + adj. + a / such + (a) + adj. , the same等词修饰时，引导词只能用as，而不用which。
如：She is so nice a girl as we all like. 她是个我们大家都喜欢的如此好的女孩。
It is such an interesting book as we all want to read. 它是本我们大家都想读的有趣的书。
上面两句中的as就不能用which替换。
(2)as 在从句中常作宾语；作主语时，从句的谓语动词常为系动词，即：系表结构或被动结构。
如：As you expected, he turned up on time. 正如你所愿，他按时到了。
As is said above, he has conquered the difficulty. 正如上面所说，他征服了困难。
(3)当非限制性定语从句放到主句的前面时，引导词只能用as，而不用whi ch。
如：As is planned, we got there before eight. 正如计划，我们再把店前到达了那儿。
(4)As引导的非限制性定语从句指表示积极的意义，与主句是顺理成章的关系，绝不能与之矛盾。
若非限制性定语从句表示一种消极的意义，则只用which。
如：He has succeeded in his career, as / which we all hope. 他在事业中成功了，这正是我们大家所希望的。
Her grandma died last week, which made her very sad. 她的奶奶逝世了，这使得她很悲伤。
(5)当非限制性定语从句的引导词前面有介词时，只能用which, 而不可用as。
如：He has a new computer, for which he paid nearly ten thousand yuan. 他有一台新电脑，这台电脑花了他将近一万元。
(6) 当关系代词代替主句中的宾语从句或复合结构(如：宾+补；不定式短语；动词-ing形式短语等) 时，一般只能用which, 而不用as。
如：She told us that there was something wrong with her bike, which was tru e。
她告诉我们说她的单车出了毛病，这话是真的。
He asked her to help him with his English, which she did. 他请她教他学英语，她的确帮了。
(7) 关系代词仅代表主句中的谓语部分时，从句中谓语部分被省略而只保留情态动词的否定式或助动词否定式，引导词一般只用which, 而不用as。
如：He speaks English very fluently, which I can’t. 他的英语说得非常流利，这我可不行。
(8)关系代词作定语修饰后面的名词时，一般只用which, 而不用as。
如：He suggested going swimming in the river, which idea we agreed with.他提议去河里游泳，我们就同意了他的想法。